Design of Concrete Retaining Wall as per BS 8110:2005
Retaining walls provide lateral support to vertical slopes of soil. They retain soil which would otherwise collapse into a more natural shape. The retained soil is sometimes referred to as backfill.Retaining walls can be constructed of many different materials and with a variety of building techniques.
All advice or information from the British Cement Association and/or The Concrete Centre is intended for those who will evaluate the significance and limitations of its contents and take responsibility for its use and application. No liability (including that for negligence) for any loss resulting from such advice or information is accepted by the BCA, TCC or their subcontractors, suppliers or advisors. Users should note that all TCC software and publications are subject to revision from time to time and should therefore ensure that they are in possession of the latest version.
Free topography Data Sources – Digital Elevation Models
1. Space Shuttle Radar Topography Mission (SRTM)
NASA only needed 11 days to capture Shuttle Radar Topography Mission (SRTM) 30-meter digital elevation model. Back in February 2000, the Space Shuttle Endeavour launched with the SRTM payload.
Using two radar antennas and a single pass, it collected sufficient data to generate a digital elevation model using a technique known as interferometric synthetic aperture radar (inSAR). C-Band penetrated canopy cover to the ground better but SRTM still struggled in sloping regions with foreshortening, layover and shadow.
In late 2014, the United States government released the highest resolution SRTM DEM to the public. This 1-arc second global digital elevation model has a spatial resolution of about 30 meters. Also, it covers most of the world with absolute vertical height accuracy of less than 16m.
Below, shaded relief images of deeply eroded volcanic terrain in northeast Tanzania demonstrate the improved nature of the highest-resolution SRTM data now being released. The image at left has data samples spaced every 90 meters (295 feet); the image at right has samples spaced every 30 meters (98 feet).
2. ASTER Global Digital Elevation Model
ASTER GDEM is an easy-to-use, highly accurate DEM covering all the land on earth, and available to all users regardless of size or location of their target areas.
Anyone can easily use the ASTER GDEM to display a bird’s-eye-view map or run a flight simulation, and this should realize visually sophisticated maps. By utilizing the ASTER GDEM as a platform, institutions specialized in disaster monitoring, hydrology, energy, environmental monitoring etc. can perform more advanced analysis.
The ASTER Global Digital Elevation Model (ASTER GDEM) is a joint product developed and made available to the public by the Ministry of Economy, Trade, and Industry (METI) of Japan and the United States National Aeronautics and Space Administration (NASA). It is generated from data collected from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), a spaceborne earth observing optical instrument.
The first version of the ASTER GDEM, released in June 2009, was generated using stereo-pair images collected by the ASTER instrument onboard Terra. ASTER GDEM coverage spans from 83 degrees north latitude to 83 degrees south, encompassing 99 percent of Earth’s landmass.
The improved GDEM V2 (released October 17, 2011) adds 260,000 additional stereo-pairs, improving coverage and reducing the occurrence of artifacts. The refined production algorithm provides improved spatial resolution, increased horizontal and vertical accuracy, and superior water body coverage and detection. The ASTER GDEM V2 maintains the GeoTIFF format and the same gridding and tile structure as V1, with 30-meter postings and 1 x 1 degree tiles.
Version 2 shows significant improvements over the previous release. However, users are advised that the data contains anomalies and artifacts that will impede effectiveness for use in certain applications. The data are provided “as is,” and neither NASA nor METI/Japan Space Systems (J-spacesystems) will be responsible for any damages resulting from use of the data.
3. JAXA’s Global ALOS 3D World
ALOS World 3D is a 30-meter resolution digital surface model (DSM) captured by the Japan Aerospace Exploration Agency’s (JAXA). Recently, this DSM has been made available to the public.
The neat thing about is that it is the most precise global-scale elevation data now. It uses the Advanced Land Observing Satellite “DAICHI” (ALOS) based on stereo mapping from PRISM.
JAXA has been processing about 100 digital 3D maps per month as part of our engineering validation activities of DAICHI so for. As we conducted research and development for full automatic and mass processing map compilations, we now have a perspective to process 150,000 maps per month. By applying our research and development results, we will start the 3D map processing in March 2014 to complete the global 3D map in March 2016. JAXA will commission the compiling work and service provision to NTT DATA Corporation and Remote Sensing Technology Center (RESTEC), Japan.
In order to popularize the utilization of the 3D map data, JAXA will also prepare global digital elevation model (DEM) with lower spatial resolution (of about 30 meters under our current plan) to publish it as soon as it is ready. Its use will be free of charge. We expect that data from Japan will become the base map for all global digital 3D maps, and contribute to the expansion of satellite data utilizations and the industrial promotion, science and research activities as well as the Group on Earth Observations.
4. Light Detection and Ranging (LiDAR)
You might think that finding LiDAR is a shot in the dark.
But it’s not anymore.
Slowly and steadily, we are moving towards a global LiDAR map.
With Open Topography topping the list at #1, we’ve put together a list of some of the 6 best LiDAR data sources available online for free.
Because nothing beats LiDAR for spatial accuracy. After you filter ground returns, you can build an impressive DEM from LiDAR.
And if you still can’t find anything in the link above, try your local or regional government. If you tell them what you are using it for, they sometimes hand out LiDAR for free.
With the advent of the digital era, rendering software has undergone a plethora of changes. The demand from users of 3D rendering software coupled with technological advancements has influenced the industry to progress over the years. The need has helped the industry revolutionize renderings that are life-like and realistic, thus appealing to clients seeking such services.
One outstanding feature is the active rendering plug-ins that come with the software. The feature has presented a wide array of options for users that can sometimes make it chaotic to use especially for those new to it. Designers and architects often stick to the 3D rendering software they used while in school and update their knowledge with any new updated versions of the software.
Nevertheless, you may be new to the industry or just seeking to expand your tech/software savvy to new visualization heights. It is essential to narrow down your search to what’s best suited for your needs.
Here is a collection of rendering software considered as popular in the industry:
V-Ray
V-Ray 3D rendering software is considered as top tier by most of its users. It was developed by the Chaos Group to provide you with the most realistic visualization features. Its latest version (VRay 3.6) was launched in late 2017 with improvements that make its predecessors (version 3.4 and 3.5) look inferior. The improvements are based on the quality of realistic visualization and speeds in rendering.
Pre-loaded final textures like hair, fur, and grass cut rendering time by almost 50% making total rendering time even faster. Adaptive lights algorithm is one of the accelerated lens effects enhanced in VRay. It allows you to adjust glare and bloom of light which will make your final render realistic. Otherwise, it is compatible with various plug-ins such as Cinema 4D, Autodesk Revit, 3DS Max and Google Sketch-up among others.
A review from most users suggests that the engine contains a wide variety of options which could make it difficult to use. The best solution to the problem is to use online tutorials to learn from.
Maxwell Render
Next Limit Technologies developed Maxwell in Madrid, Spain. You might have heard that it is too slow for rendering images. It may be true as it takes a long time to render extraordinarily sharp and realistic visuals. The rendering software uses a unique lighting engine called “unbiased rendering” responsible for using real-life modeling techniques, unlike other rendering software which uses tricks and shortcuts and results in fewer quality images.
The tradeoff in best quality images is the long rendering time the engine takes. Why not be patient for the best quality images? Besides, why not wait for greatness? The stand-alone software is mostly used in the film and animation industry.
Octane Render
Octane Render is the newcomer to the industry and has a couple of tricks above its sleeve. Developed by Refractive Software Ltd and OTOY, it is classified as a real-time 3D unbiased rendering application; it’s the first commercially available unbiased renderer to work on the Graphics Processing Unit (GPU). This attribute helps the render engine use the power of your graphics card to facilitate most of its render calculations. So the better your graphics card, the better the rendering speeds.
On the contrary, Octane does not have a wealth of resources like VRay and Mental Ray, but its unique dependence on the GPU qualifies it to be among the popular rendering software. As it is new to the game, you may not find many tutorial videos online, and its most significant downside is that it will only work with NVIDIA cards. Sorry ATI card users.
Cinema 4D
Cinema 4D brings something different to the table. It is not just a 3D rendering software but also includes animation and motion graphics capabilities. MAXON Computer GmbH developed the application in Germany. It is capable of the typical 3D modeling applications and an added advantage of procedural and polygonal/subd (Catmull–Clark subdivision surface) modeling.
Cinema 4D works as the best ArchiCAD or Vectorworks add-on, especially if you’re an architect on the row for defiance in sticking by ArchiCAD. The programs work seamlessly.
Modo
Modo makes a name in mainstream listings among famous rendering giants like Mental Ray and VRay for its wholesomeness. It makes a list because of its ability to model and render from the same application. No more cumbersome imports or exports which require you to switch between different halves of the same rendering software.
Out of all renderers with preview capabilities, Modo leads the day with the fastest processing time. It gives fast and quality realistic scenes, unlike other engines which compromise quality while giving you a preview. Its major drawback is that it does not have too many control features.
3DS Max
3DS Max was formerly known as 3D Studio and Studio Max. The software was developed and produced by Autodesk Media and Entertainment. It may not necessarily be the most acclaimed rendering software but certainly earned its place amongst the most popular. 3DS Max also comes with an onboard renderer that can work with a 3D modeling software. It interfaces well with AutoCAD and Revit, which are Autodesk products.
Note that Revit also has rendering capabilities but is limited in its results and flexibility. This is where 3Ds saves the day by allowing an import and satisfactorily manipulates textures intuitively to render visuals of the best quality.
Honorable Mention: Mental Ray (development discontinued ?)
Developed by Mental Images (owned by the renowned NVIDIA graphics card maker), Mental Ray earns its closest comparison to V-Ray from most of its users in terms of quality of render images towards realistic effects. Although personal preferences between the two engines may differ, what is apparent is that Mental Ray is a friendlier rendering engine. It may not match the level of realism V-Ray is capable of, but its simplicity to use qualifies it to be considered as a top-tier renderer.
Developed in 2007, the main aim was to produce a universal rendering engine that can be used by designers, architects, and artists. Its usefulness is mainly pegged on its versatility and ease of use especially advantageous to architects. There is a lot to learn about any rendering software, but Mental Ray doubles up as the best for first-time users.
Lumion
Lumion is a 3D rendering software that has been developed to integrate with CAD software. Its ease of use makes it suitable for designers and architects who want to render in-house. In addition, Lumion renders in real-time, making it an ideal tool to develop the look and feel of a product.
To enhance your renders, this 3D rendering software includes an extensive library of skies, water, grass, materials, plants, people, trees and other assets. Impressively, Lumion can handle landscapes populated with thousands of these assets.
The large feature-set makes this 3D rendering software an excellent addition to any architect’s toolbox.
LuxRender
LuxRender is an unbiased/biased 3D rendering software that is available under an OpenSource license. On a wide range of features, LuxRender can compete with commercial rendering solutions: The materials used are physically based, thus enabling photorealistic results.
Even complex phenomena like subsurface scattering and volumetrics are supported by LuxRender. To help minimize the overall render time, users can choose to render in biased mode. To the same end, instanced objects may be used in this 3D rendering software.
Because of LuxRender’s impressive range of features, it is an excellent 3D rendering software for special effects and architectural visualization.
The best apps for architects can be hard to find when you are working on sketches, with project owners, or managing a team. That is why we looked for the best apps for architects so you would not have to.
On our search for the top apps for architects, we found a wide range of apps: architecture calculators, architecture prioritization apps, architecture drawing apps, and more.
Here is a list of the top apps for architects that we found:
Best Apps For Architects
For Architecture Calculators
Concept App by Fast + Epp
Stemming from clients’ desire to assess project feasibility before putting pencil to paper, structural engineers at Fast + Epphave developed CONCEPT – a free iPhone app that allows architects and engineers to calculate member depths and browse project photos for structural expressions.
CONCEPT’s depth calculator uses typical span-to-depth ratios for common steel, concrete, and wood members. The user simply indicates if the information they’re inputting is a roof or floor, with the internal calculator determining an approximate depth. Additional information is provided to qualify the load assumptions and tributary areas.
Users are able to share search and calculation results by emailing them to co-workers and clients for discussion prior to the first design charrette.
Paul Fast, the Partner of Fast + Epp states “Concept is a free app because we wanted to make it readily accessible to as many architects and designers as possible. We’re confident this is going to be a really useful tool.
For Floor Plans
Magicplan
Magicplan is the post-PC floor plan creation technology for everyone, and it is particularly helpful for architects. Its augmented reality features let you create a floor plan simply by taking pictures. With Magicplan, you can easily generate complete work estimates, furnish a home, or plan your next DIY project.
For Drafting
Scala Architectural And Engineering Scale
Scala Architectural and Engineering Scale provides a new way to measure printed drawings on the go and at your desk. It includes standard imperial architectural, metric architectural, and engineering scales in a handy app. You can also create custom variable scales in case your drawings aren’t to a known scale.
For Architecture Prioritization
Priority Matrix
Priority Matrix is a prioritization app that helps architect firms manage resources, increase visibility, and track progress of all of their projects.
Within Priority Matrix, you can use the tool to:
Visualize your team’s workload by using the platform to view how work is distributed across your team. This means that you can tell which members of your team have the most on their plate, and which members you can assign more work to.
Determine which items are of high priority so you and your team can focus on what matters most.
Keep track of tasks by inputting tasks into Priority Matrix along with notes, screenshots, and a due date. In addition, you can delegate tasks through the app, and communicate any questions or comments under the task to keep things organized.
Generate Simple Reports like visual Gantt charts, or a report to show how many tasks were completed yesterday by specific members of your team.
Store files, including those large CAD files so everything is in one place.
Keep clients in the loop, using the read-only feature to send project owners project updates; you can even send them over your Gantt-chart.
For Architecture Jobs and Recruitment
Design & Construct
Even though Design & Construct is not an app, we felt it was necessary to include it because it should be a tool on your list to meet your recruiting needs.
Design & Construct is a leading Australian-based recruitment agency, providing a specialized approach to recruitment in the Architecture and Construction industry.
By working with a specialist recruiter, you can be sure to know about the best opportunities as they rise. A recruiter has the technical insights into Australia’s architecture jobs market, meaning they know what employers are looking for. Whether it’s architecture, interior design, landscape design, or urban planning roles, specialists will have the contacts.
As their company states, “Tailored recruitment is at the heart of Design & Construct, and the key reason why 95% of clients return to us and 97% are happy to refer us to their most trusted industry contacts.”
For File Sharing
FileCloud
FileCloud is a file sharing, sync and mobile access solution. FileCloud has many capabilities, including:
File Remote Access and Sharing which allows businesses to create their own, branded file sharing, sync, and mobile access solution for their employees, customers and partners.
File Sync, allowing for effortless file synchronization across users computers, smart phones and tablets, so everyone can work together anywhere from any device.
Endpoint Backup and DLP, creating secure backup and Data Leak Prevention (monitor, prevent and fix) across all your user’s devices (Computers, Mobile Phones/Tablets).
In addition, FileCloud offers deployment flexibility where users can self-host on their premise, host in the cloud, or create a hybrid solution.
For Presentation
GRAPHISOFT BIMx
GRAPHISOFT BIMx is an award-winning communication and presentation app.
BIMx features virtual reality (VR) functionality. This enhanced functionality provides architectural and interior design firms an immersive way to share their projects. BIMx with Google CardboardTM viewer allows users to navigate through an ARCHICAD model in virtual 3D with a simple turn of the head.
For Creating 3-D Models
Shapr3D
Shapr3D is the world’s first professional 3D modeling tool designed specifically for iPad Pro.
Shapr3D is the only truly mobile CAD app. It offers you a quick but precise way to create 3D models from scratch. You can easily create 2D sketches and turn them into 3D models using various tools.
The program is mostly used by engineers, industrial designers, product designers, 3D hobbyists, and architects.
Famous users include Patrick Jouin (one of France’s most acclaimed designers), Rodrigo Otazu (who designs jewelery for Madonna, Bruno Mars, Lady Gaga and Swarowksi), and Claas Kuhnen (industrial design professor at Wayne State University).
Architecture Sketching Apps
Archisketch
Archisketch is a scale-aware sketching program ideal for architects, interior and landscape designers, product designers, design students, or anyone working with design on an iPad. Inspired by the tradition of sketching on a tracing pad, Archisketch brings sketching and the early stages of a design process into the modern era on an iPad.
Archisketch helps architects and designers visualize, capture, and explore their ideas using layers, symbols, colors, dimension guidelines, 2D grids, isometric and axonometric 3D grids, and even smart one and two-point perspectives for 3D. When finished, drawings can be printed to scale directly from the iPad up to A1 size, or exported to PDF, which can be included in a CAD application, or even uploaded to the Photos App or the Adobe Creative Cloud.
SmartDraw
With SmartDraw, you get the power of CAD software without the CAD hassles.
SmartDraw gives you powerful tools and a broad selection of architectural templates to help you plan your next office, building or home project.
First, you choose a template and add symbols from the thousands included. You can draw your plan using any scale selected from the standard architectural, civil engineering, mechanical engineering, and metric scale, or you can even define your own custom scale.
In the program, you can import DXF or Visio files, add annotation layers, print to scale, change sizing by just typing in dimensions, and more.
For Experience Tracking Apps
My AXP
Reporting hours for the Architectural Experience Program™ (AXP™) has never been easier, thanks to NCARB’s My AXP mobile app! Licensure candidates can log hours, submit experience reports to supervisors, review their progress, and more. And it is available for free on Apple and Android devices.
For Home Remodeling and Design
Houzz
Houzz is a platform for home remodeling and design, providing people with everything they need to improve their homes from start to finish. From decorating a small room to building a custom home and everything in between, Houzz connects millions of homeowners, home design enthusiasts, and home improvement professionals across the country and around the world.
With the largest residential design database in the world and a vibrant community empowered by technology, Houzz is the easiest way for people to find inspiration, get advice, buy products and hire the professionals they need to help turn their ideas into reality.
The Houzz app is reimagining the home shopping experience, with unique features that are changing the way people shop for and design their homes, including:
View in my room lets app users virtually place and see over 9 million products from the Houzz Shop in their own homes before they buy
Sketch makes it easy for homeowners and home professionals to communicate ideas and collaborate directly on any of the more than 14 million photos on Houzz, or images from their own library and around the web, by adding measurements, notes, stickers, Houzz Shop products, and more. Additionally, the tool can be used to create mood boards and floor plans. Sketch allows for real-time collaboration, where multiple people can simultaneously annotate the same photo.
Visual Match is a visual recognition tool that makes it easy for people to discover and buy on Houzz the types of products and materials that inspire them in photos. Available for desktop and in the Houzz app for iPhone, iPad, and Android, Visual Match applies deep learning technology to scan the more than 14 million photos on Houzz to identify furniture and decor in living spaces and surface visually similar inventory from the Houzz Shop.
Plaans
Plaans is a documentation tool for architects, engineers, surveyors, facility managers, interior designers, and many more.
The app provides a wide range of features to support the whole documentation process – from photos, voice memos, and notes, to measurements and sketches. It will always remember, where and from what direction you took a photo and at what exact position you took a note or recorded a voice memo.
Additionally, Plaans exports your data in a well-organized file and folder structure to make sure nothing gets lost and you can access your data fast and easy. For efficient teamwork, you can compile the documentation data as a ZIP file within Plaans and send it by e-mail. With that being said, Plaans automatically generates interactive plans you can view in any internet browser and easily deploy them for colleagues and clients for subsequent processing.
For Stress Management
Stop, Breathe, and Think
The architecture industry is a stressful industry to be in at times. The good thing about living in a world full of apps is that there are companies who have created apps to help you take some time and relax.
Stop, Breathe,and Think is great because it generates meditations that you can do after plugging in how you feel into the app (for example, stressed out, angry, excited). The meditations are short enough that you can pull in a quick one during your lunch, or at the end of your work day.
For travel
Trip Advisor
Trying to plan a vacation to de-stress? Trying to find a hotel to stay at when you have to check out a site? Trip advisor will take away the stress that comes from searching.
With Trip Advisor, not only can you read reviews for hotels, restaurants, and attractions, but Trip Advisor will compare prices of hotels that you can stay at when you are away, saving you a lot of clicks.
Expedia
Like Trip Advisor, if you are planning on going on a vacation or a business trip, Expedia will save you a ton of clicks so that you can find the least expensive airfare, hotels, car rentals and more when flying to your destination. This way, you will spend less time to make your arrangements and spend less of your hard earned money when you travel.
For Architecture Fashion
Warby Parker
If you spend a lot of time outdoors or on the field, you know that you always need the right pair of shades in order to keep your eyes safe from the rays. Just because you are working, does not mean you cannot be hip on the field.
Warby Parker sells prescription eyeglasses and sunglasses starting at $95 ($175 for prescription sunglasses), which you can order online, in store, or over the phone (888.492.7297, 9a.m.–9p.m. ET).
The great thing about Warby Parker is that they allow you try on sunglasses before you buy them with their home try onsystem where you select five frames to test out for five days and then they ship them to you for free! They also offer a 30-day no-questions-asked return or exchange policy for all their eyewear — so there is no pressure.
Another great thing about Warby Parker is that they accept flexible spending account (FSA) dollars affiliated with major credit cards, or you can apply for reimbursement if you have an out-of-network benefit included in your insurance plan.
Used in conjunction, these apps will save you time (and money) and resources in order to get everything done efficiently and hopefully make you and your team’s job a little easier.
Written by ANDY LI – 3D architectural renderings, Animation and multimedia Product Manager in Fancy Digital Technology Co., Ltd.
Construction Equipment Earthwork & Soil Compaction
1.Cable Excavator
Cable excavators are large earthmoving machines used for heavy excavation of materials with the use of cables or wire ropes. Almost obsolete, cable excavators were once used in mining and some construction applications and usually consisted of a variety of attachments that could transform it into a backhoe, skimmer, dragline, and more. Aside from a few companies that still manufacture them, cable excavators have been replaced by hydraulic excavators due to their cheaper costs, easier operation and faster mobility.
2. Hydraulic excavators (slewing excavators)
A hydraulic excavator (digger) is a large vehicle that is designed for excavation and demolition purposes. Hydraulic excavators consist of a chassis, boom, and bucket, and move via tracks or wheels. They range in size and function, an example of which is the similar but smaller “mini excavator.” All versions are generally designed for the same purposes. Hydraulic excavators weigh between 3,000 and 2 million pounds and their speed ranges between 19 HP and 4,500 HP.
3.Backhoe excavators
Backhoe is another widely used equipment which is suitable for multiple purposes. The name itself telling that the hoe arrangement is provided on the back side of vehicle while loading bucket is provided in the front.
This is well useful for excavating trenches below the machine level and using front bucket loading, unloading and lifting of materials can be done.
4. Bulldozers (dozers)
A bulldozer is a crawler (continuous tracked tractor) equipped with a substantial metal plate (known as a blade) used to push large quantities of soil, sand, rubble, or other such material during construction or conversion work and typically equipped at the rear with a claw-like device (known as a ripper) to loosen densely compacted materials.
Bulldozers can be found on a wide range of sites, mines and quarries, military bases, heavy industry factories, engineering projects and farms.
5. Scrapers
Scraper, in engineering, machine for moving earth over short distances (up to about two miles) over relatively smooth areas. Either self-propelled or towed, it consists of a wagon with a gate having a bladed bottom. The blade scrapes up earth as the wagon pushes forward and forces the excavated material into the wagon. When the wagon is filled, the gate is closed, and the material is carried to the place of disposal. The scraper is the dominant tool in highway construction.
6. Graders
Grader, in excavation, precision finishing vehicle for final shaping of surfaces on which pavement will be placed. Between its front and rear wheels a grader carries a broad mechanically or hydraulically controlled blade that can be extended from either side. Either end of the blade can be raised or lowered. Graders may be used for shallow ditching, but most models are used to assist other earth-moving equipment and to smooth roads, fills, and cuts.
7. Compactors
A compactor is a machine or mechanism used to reduce the size of material such as waste material or bio mass through compaction. A trash compactor is often used by a home or business to reduce the volume of trash it produces.
The popular RC-spreadsheets package version 4 was issued following the amendment to the UK National Annex to Eurocode 2 in December 2009. These Excel spreadsheets are intended as aids for design to both Eurocode 2 and BS 8110-1:1997.
Version 4B.2 provides updates to Version 4B.1 that reflect developments and improvements particularly with respect to punching shear, column design and pilecap design as well as applying bug fixes.
What does RC Spreadsheets do? For the experienced engineer, the spreadsheets allow the rapid production of clear and accurate design calculations. For post-graduates and new engineers they encourage understanding of concrete design and help the gaining of experience by studying ‘what if’ scenarios. The individual user is able to answer their own questions by chasing through the cells to understand the logic used.
Since their release in January 2000, the RC Spreadsheets have proved to be enormously popular. They are written for engineers by engineers. The original spreadsheets have evolved and been added to and the usefulness and robustness of the product have been enhanced by users feedback. If you have any comments please let us know.
Mineral-producing bacteria have been found that could help mend micro-cracking in concrete. Dr Henk Jonkers, a micro-biologist at Delft University, talked to Ingenia about research developments in producing bioconcrete that could bring benefits for civil engineering projects.
Self-healing concrete could solve the problem of concrete structures deteriorating well before the end of their service
life. Concrete is still one of the main materials used in the construction industry, from the foundation of buildings to the structure of bridges and underground parking lots.
Traditional concrete has a flaw, it tends to crack when subjected to tension. A healing agent that works when bacteria embedded in the concrete convert nutrients into limestone has been under development at the Civil Engineering and Geosciences Faculty in Delft since 2006.
The project is part of a wider programme to study the self-healing potential of plastics, polymers, composites, asphalt and metals as well as concrete. Dr Henk Jonkers, a microbiologist who specialises in the behaviour of bacteria in the environment, has developed self-healing concrete in the laboratory and full-scale outdoor testing will start in 2011. The
first self-healing concrete products (successful research results permitting) are expected to hit the market in two years’
time and are expected to increase the lifespan of many civil engineering structures.
Jonkers has worked closely with civil and structural engineers to learn about the properties of concrete and steel reinforcement, and develop the concrete. “For a biologist to work with civil engineers to incorporate living matter into
structural concrete material is in itself a great innovation,” he says.
WHY THE NEED ?
Concrete will continue to be the most important building material for infrastructure but most concrete structures are
prone to cracking. Tiny cracks on the surface of the concrete make the whole structure vulnerable because water seeps in to degrade the concrete and corrode the steel reinforcement, greatly reducing the lifespan of a structure.
Concrete can withstand compressive forces very well but not tensile forces. When it is subjected to tension it starts to crack, which is why it is reinforced with steel; to withstand the tensile forces.
Structures built in a high water environment, such as underground basements and marine structures, are particularly vulnerable to corrosion of steel reinforcement. Motorway bridges are also vulnerable because salts used to de-ice the roads penetrate into the cracks in the structures and can accelerate the corrosion of steel reinforcement. In many civil engineering structures tensile forces can lead to cracks and these can occur relatively soon after the structure is built.
Repair of conventional concrete structures usually involves applying a concrete mortar which is bonded to the damaged surface. Sometimes, the mortar needs to be keyed into the existing structure with metal pins to ensure that it
does not fall away. Repairs can be particularly time consuming and expensive because it is often very difficult to gain
access to the structure to make repairs, especially if they are underground or at a great height.
Self-healing concrete is a product that will biologically produce limestone to heal cracks that appear on the surface of concrete structures. Specially selected types of the bacteria genus Bacillus , along with a calcium-based nutrient known as calcium lactate, and nitrogen and phosphorus, are added to the ingredients of the concrete when it is being mixed. These self-healing agents can lie dormant within the concrete for up to 200 years.
However, when a concrete structure is damaged and water starts to seep through the cracks that appear in the concrete, the spores of the bacteria germinate on contact with the water and nutrients. Having been activated, the bacteria start to feed on the calcium lactate.
As the bacteria feeds oxygen is consumed and the soluble calcium lactate is converted to insoluble limestone. The limestone solidifies on the cracked surface, thereby sealing it up. It mimics the process by which bone fractures in
the human body are naturally healed by osteoblast cells that mineralise to re-form the bone. The consumption of oxygen during the bacterial conversion of calcium lactate to limestone has an additional advantage. Oxygen is an essential element in the process of corrosion of steel and when the bacterial activity has consumed it all it increases the durability of steel reinforced concrete constructions.
The bioconcrete healing itself (Image Courtesy of Delft University)
The two self-healing agent parts (the bacterial spores and the calcium lactate-based nutrients) are introduced to the concrete within separate expanded clay pellets 2-4 mm wide, which ensure that the agents will not be activated during the cement-mixing process. Only when cracks open up the pellets and incoming water brings the calcium lactate into contact with the bacteria do these become activated. Testing has shown that when water seeps into the concrete, the bacteria germinate and multiply quickly. They convert the nutrients into limestone within seven days in the laboratory.
Outside, in lower temperatures, the process takes several weeks.
FINDING THE RIGHT BACTERIA
The starting point of the research was to find bacteria capable of surviving in an extreme alkaline environment.
Cement and water have a pH value of up to 13 when mixed together, usually a hostile environment for life:
most organisms die in an environment with a pH value of 10 or above.
The search concentrated on microbes that thrive in alkaline environments which can be found in natural environments, such as alkali lakes in Russia, carbonate-rich soils in desert areas of Spain and soda lakes in Egypt. Samples of endolithic bacteria (bacteria that can live inside stones) were collected along with bacteria found in sediments in the lakes. Strains of the bacteria genus Bacillus were found to thrive in this high-alkaline environment. Back at Delft University the bacteria from the samples were grown in a flask of water that would then be used as the part of the water mix for the concrete.
Different types of bacteria were incorporated into a small block of concrete. Each concrete block would be left for two months to set hard. Then the block would be pulverised and the remains tested to see whether the bacteria had survived.
It was found that the only group of bacteria that were able to survive were the ones that produced spores comparable to plant seeds. Such spores have extremely thick cell walls that enable them to remain intact for up to 200 years while waiting for a better environment to germinate.
They would become activated when the concrete starts to crack, food is available, and water seeps into the structure.
This process lowers the pH of the highly alkaline concrete to values in the range (pH 10 to 11.5) where the bacterial spores become activated.
Finding a suitable food source for the bacteria that could survive in the concrete took a long time and many different nutrients were tried until it was discovered that calcium lactate was a carbon source that provides biomass.
If it starts to dissolve during the mixing process, calcium lactate does not interfere with the setting time of the concrete.
A landslide is defined as the movement of a mass of rock, debris, or earth down a slope due to gravity. The materials may move by falling, toppling, sliding, spreading, or flowing.
Landslide Animation:
What causes a landslide?
Almost every landslide has multiple causes. Slope movement occurs when forces acting down-slope (mainly due to gravity) exceed the strength of the earth materials that compose the slope. Landslides can be triggered by rainfall, snowmelt, changes in water level, stream erosion, changes in ground water, earthquakes, volcanic activity, disturbance by human activities, or any combination of these factors.
What are submarine landslides?
Earthquake shaking and other factors can also induce landslides underwater. These landslides are called submarine landslides. Submarine landslides sometimes cause tsunamis that damage coastal areas.
Where do landslides occur?
Landslides in the United States occur in all 50 States. The primary regions of landslide occurrence and potential are the coastal and mountainous areas of California, Oregon, and Washington, the States comprising the intermountain west, and the mountainous and hilly regions of the Eastern United States. Alaska and Hawaii also experience all types of landslides.
How fast do landslide travel?
Landslides can move slowly, (millimeters per year) or can move quickly and disastrously, as is the case with debris flows. Debris flows can travel down a hillside at speeds up to 200 miles per hour (more commonly, 30 – 50 miles per hour), depending on the slope angle, water content, volume of debris, and type of earth and debris in the flow. These flows are initiated by heavy periods of rainfall, but sometimes can happen as a result of short bursts of concentrated rainfall or other factors in susceptible areas. Burned areas charred by wildfires are particularly susceptible to debris flows, given certain soil characteristics and slope conditions.
Why study landslides?
Landslides are a serious geologic hazard. It is estimated that in the United States they cause in excess of $1 billion in damages and from about 25 to 50 deaths each year. Globally, landslides cause billions of dollars in damages and thousands of deaths and injuries each year.
Who is most at risk for landslides?
As people move into new areas of hilly or mountainous terrain, it is important to understand the nature of their potential exposure to landslide hazards, and how cities, towns, and counties can plan for land-use, engineering of new construction and infrastructure, and other measures which will reduce the costs of living with landslides. Although the physical causes of many landslides cannot be removed, geologic investigations, good engineering practices, and effective enforcement of land-use management regulations can reduce landslide hazards.
Do human activities cause landslides?
Yes, in some cases human activities can be a contributing factor in causing landslides. Many human-caused landslides can be avoided or mitigated. They are commonly a result of building roads and structures without adequate grading of slopes, of poorly planned alteration of drainage patterns, and of disturbing old landslides.
Where can I find landslide information for my area?
The USGS National Landslide Information Center (NLIC) is a part of the U.S. Geological Survey Landslide Hazards Program that collects and distributes all forms of information related to landslides. The NLIC is designed to serve landslide researchers, geotechnical practitioners engaged in landslide stabilization, and anyone else concerned in any way with landslide education, hazard, safety, and mitigation. Every state in the US has a geoscience agency and most have some landslide information. The Association of American State Geologists provides links to the State Geologist for every state.
What was the most expensive landslide to fix in the United States?
The Thistle, Utah, landslide cost in excess of $200 million dollars to fix. The landslide occurred during the spring of 1983, when unseasonably warm weather caused rapid snowmelt to saturate the slope. The landslide destroyed the railroad tracks of the Denver and Rio Grande Western Railway Company, and the adjacent Highway 89. It also flowed across the Spanish Fork River, forming a dam. The impounded river water inundated the small town of Thistle. The inhabitants of the town of Thistle, directly upstream from the landslide, were evacuated as the lake began to flood the town, and within a day the town was completely covered with water. Populations downstream from the dam were at risk because of the possible overtopping of the landslide by the lake. This could cause a catastrophic outburst of the dam with a massive flood downstream. Eventually, a drain system was engineered to drain the lake and avert the potential disaster.
How many deaths result from landslides?
An average of between 25 and 50 people are killed by landslides each year in the United States. The worldwide death toll per year due to landslides is in the thousands. Most landslide fatalities are from rock fall, debris-flows, or volcanic debris flows.
What should I know about wildfires and debris flows?
Wild land fires are inevitable in the western United States. Expansion of human development into forested areas has created a situation where wildfires can adversely affect lives and property, as can the flooding and landslides that occur in the aftermath of the fires. There is a need to develop tools and methods to identify and quantify the potential hazards posed by landslides produced from burned watersheds. Post-fire landslide hazards include fast-moving, highly destructive debris flows that can occur in the years immediately after wildfires in response to high intensity rainfall events, and those flows that are generated over longer time periods accompanied by root decay and loss of soil strength. Post-fire debris flows are particularly hazardous because they can occur with little warning, can exert great impulsive loads on objects in their paths, and can strip vegetation, block drainage ways, damage structures, and endanger human life. Wildfires could potentially result in the destabilization of pre-existing deep-seated landslides over long time periods.
How do landslides cause tsunamis?
Tsunamis are large, potentially deadly and destructive sea waves, most of which are formed as a result of submarine earthquakes. They may also result from the eruption or collapse of island or coastal volcanoes and the formation of giant landslides on marine margins. These landslides, in turn, are often triggered by earthquakes. Tsunamis can be generated on impact as a rapidly moving landslide mass enters the water or as water displaces behind and ahead of a rapidly moving underwater landslide.
What are some examples of landslides that have caused tsunamis?
The 1964 Alaska earthquake caused 115 deaths in Alaska alone, with 106 of those due to tsunamis generated by tectonic uplift of the sea floor, and by localized subareal and submarine landslides. The earthquake shaking caused at least 5 local slide-generated tsunamis within minutes after the shaking began. An eyewitness account of the tsunami caused by the movement and landslides of the 1964 Alaska earthquake.
Research in the Canary Islands concludes that there have been at least five massive volcano landslides that occurred in the past, and that similar large events may occur in the future. Giant landslides have the potential of generating large tsunami waves at close and also very great distances and would have the potential to devastate large areas of coastal land as far away as the eastern seaboard of North America.
Rock falls and rock avalanches in coastal inlets, such as those that have occurred in the past at Tidal Inlet, Glacier Bay National Park, Alaska, have the potential to cause regional tsunamis that pose a hazard to coastal ecosystems and human settlements. On July 9, 1958, a magnitude M 7.9 earthquake on the Fairweather Fault triggered a rock avalanche at the head of Lituya Bay, Alaska. The landslide generated a wave that ran up 524 m on the opposite shore and sent a 30-m high wave through Lituya Bay, sinking two of three fishing boats and killing two persons.
How soon does the danger of landslides end after the rain stops?
It’s not possible to exactly predict the number of days or weeks that landslides remain a danger after heavy rain. Residents near mountain slopes, canyons, and landslide prone areas should stay alert even after heavy rain subsides.
Why is southern California vulnerable to landslides?
Areas that have been burned by recent wildfires are highly susceptible to debris-flow activity that can be triggered by significantly less rainfall than that which triggers debris flows from unburned hill slopes.
What was the biggest landslide in the world?
The world’s biggest historic landslide occurred during the 1980 eruption of Mount St. Helens, a volcano in the Cascade Mountain Range in the State of Washington, USA. The volume of material was 2.8 cubic kilometers (km).
What was the biggest prehistoric landslide?
The world’s biggest prehistoric landslide, discovered so far on land, is in southwestern Iran, and is named the Saidmarreh landslide. The landslide is located on the Kabir Kuh anticline in Southwest Iran at 33 degrees north latitude, 47.65 degrees east longitude. The landslide has a volume of about 20 cubic kilometers, a depth of 300 m, a travel distance of 14 km and a width of 5 km. This means that about 50 billion tons of rock moved in this single event!
Some single landslide events have killed numbers in excess of the populations of small countries.
Landslides are life-threatening events that can make it seem as though the world we live upon is crumbling around us. Those landslides listed below are some of the deadliest in recorded human history, each taking away human life by the thousands.
10. Diexi Slides, Sichuan, China, August 1933 (3,000+ deaths)
On August 5, 1933, a strong earthquake triggered a massive landslide in Diexi, Mao County, Szechwan, China. The event, known as the Diexi Slides, claimed more than 3,000 lives, and destroyed many villages within the affected region. The old town of Diexi suffered the worst fate of all as it sank into the landslide-created dam below.
9. Khait Landslide, Tajikstan, July 1949 (4,000 deaths))
For centuries, the mountainous belt running through Central Asia has witnessed a large number of disasters involving earthquake-triggered landslides. One such natural catastrophe occurred in July of 1949, when the 7.4 magnitude Khait Earthquake triggered hundreds of landslides near the southern limits of the Tien Shan ranges in central Tajikistan. The adjacent valleys of Yasman and Khait were the most affected by these earthquake-induced landslides. The Khait Landslide involved rockslides with saturated loess travelling at an estimated average velocity of around 30 meters per second. Approximately 4,000 people were killed in this tragic natural disaster.
8. 62 Nevado Huascaran Debris Fall, Ranrahirca, Peru, January 1962 (4,500 deaths)
Mount Huascarán is a famous Peruvian mountain with a snowcapped peak that rises to a height of 22,205 feet. In January of 1962, a thaw triggered the breaking off of a portion of the north summit of the mountain, leading to a landslide/avalanche that led to the tragic death of nearly 4,500 people. The avalanche, locally referred to as ‘Huayco’, involved a massive ice sheet that was estimated to be about 1 kilometer wide and 40 feet high. As the ice sheet moved rapidly down the slopes, it gathered rock and debris from the mountain and strengthened in force, completely burying several villages in Ranrahica underneath it.
7. Huaraz Debris Flows, Ancash, Peru, December 1941 (5,000 deaths)
In December of 1941, the residents of Huaraz, a Peruvian city in the Ancash region, were completely unaware that a retreating glacier tongue above their city would soon be responsible for wreaking havoc its people and claim thousands of the lives living within. Just before dawn on December 13, 1941, disaster struck the Peruvian city when a landslide resulted in glacial ice crashing down into Lake Palcacocha, generating huge waves that completely destroyed the dam on the lake. This released large volumes of water, itself laden with mud, rock, and ice, into the valley below with an unimaginably high force. Another dam in the nearby Lake Jircacocha was also broken by the flowing glacial water, resulting in the furious waters of both of the two lakes emptying themselves onto the city of Huaraz, claiming more than 5,000 lives in the process.
6. Kelud Lahars, East Java, Indonesia, May 1919 (5,000+ deaths)
Mount Kelud, in Eastern Java, Indonesia, is quite infamous as an extremely active, hazardous volcano, and one which has erupted about 30 times in the past killing thousands of people in its volcanic disasters. One of the deadliest eruptions of this volcano occurred on May 19, 1919, when over 38 million cubic meters of water were expelled from the crater lake of the volcano, which had accumulated large amounts of sediment and volcanic material to form lethal lahars. The lahars moved down the mountains with high velocity and swept away and drowned all that were unfortunate enough to be in its path.
5. North India Flood mudslides, Kedarnath, India, June 2013 (5,700 deaths)
One of the worst natural disasters in the history of India occurred in June of 2013, when powerful flash floods killed around 5,700 people in the Himalayan state of Uttarakhand. Consistent cloudbursts and incessant monsoon rainfall were primarily held responsible for the disaster, which has been officially termed as a natural calamity. However, a section of environmentalists, scientists, and the educated public think otherwise. According to them, thoughtless human intervention in the Himalayan mountain ecosystem had rendered the ecosystem extremely fragile and prone to disaster. The unchecked tourism in the region had promoted the rapid growth of hotels, roads, and shops throughout the region without paying heed to the environmental laws and demands of the ecosystem. The mushrooming of hydroelectric dams in Uttarakhand was also another important factor held responsible for the environmental damage. Heavy rainfall had been previously recorded in the region which had also led to flash floods, but the devastation produced in 2013 was comparable to no earlier data. It is believed that floodwaters had no outlets this time, as most of the routes taken by the water previously were now blocked by sand and rocks. Hence, the lethal waters, laden with debris from dam construction and large volumes of mud and rocks, inundated towns and villages and buried all forms of life that came in its way.
4. 70 Nevado Huascaran Debris Fall, Yungay, Peru, May 1970 (22,000 deaths)
In May of 1970, an earthquake triggered a massive series of landslides and avalanches of rock and snow that buried the towns of Yungay and Ranrahirca. Nearly 22,000 people perished in this natural disaster. The avalanche travelled a distance of 16.5 kilometers. It ended up carrying 50-100 million cubic meters of water, mud, and rocks, which reached the village of Yungay and smothered all life forms therein under its deadly cover.
3. Armero Tragedy, Tolima, Colombia, November 1985 (23,000 deaths)
A dormant volcano, the Nevado del Ruiz in Tolima, Colombia, suddenly came to life on November 13, 1985, wreaking havoc on the nearby villages and towns, and killing as many as 23,000 people. A pyroclastic flow from the crater of the volcano had melted the glaciers in the mountain and sent deadly lahars, saturated with mud, ice, snow, and volcanic debris, rushing down the mountain at killer speeds towards the residential areas directly below it. The lahars soon engulfed the town of Armero, killing thousands there, while casualties were also reported in such other towns as Chinchiná
2. Vargas Tragedy, Vargas, Venezuela, December 1999 (30,000 deaths)
The Winter of 1999 witnessed unusually heavy rainfall in the Vargas State of Venezuela. The rainfall triggered a series of large and small flash floods and debris flows that claimed around 30,000 lives in the region. As per estimates, approximately 10% of the population of Vargas perished in the disaster. The entire towns of Carmen de Uria and Cerro Grande completely vanished under the mud bed, and a large number of homes were simply swept away into the nearby ocean.
1. Haiyuan Flows, Ningxia, China, December 1920 (100,000+ deaths)
The 8.5-magnitude Haiyuan Earthquake was the world’s second deadliest earthquake of the 20th Century. It generated a series of 675 major loess landslides causing massive destruction to lives and property. The natural calamity which struck the rural district of Haiyuan on the evening of December 16, 1920 claimed over 100,000 lives, and severely damaged an area of approximately 20,000 square kilometers. The worst affected areas included the the epicenter of the earthquake in the Haiyuan County in what is now the Ningxia Hui Autonomous Region, as well as the neighboring provinces of Gansu and Shaanxi. Haiyuan County alone lost more than 50% of its population in the disaster. One of the landslides buried an entire village in Xiji County as well.
